Heave-proof arctic piling

ABSTRACT

Piling projecting at the upper part through tundra are protected from ground movement in an upward direction due to periodic freezings and thawings of the tundra by being fixed to conically shaped collars extending down from the surface of the earth, with the base of the cone down. The conical portion thus becomes a part of the pile, mechanically speaking. If desired, the conically shaped part may be an integral part of the pile. As the liquid part of the tundra surrounding the upper part of the pile freezes, it expands radially inward against the conical surface, resulting in a downward force of sufficient magnitude to keep the pile from &#39;&#39;&#39;&#39;heaving&#39;&#39;&#39;&#39;, i.e., moving vertically upward due to freezing effects in the ground.

[4 1 Nov. 28, 1972 United States Patent Newton FOREIGN PATENTS ORAPPLICATIONS George R. Newton, Tulsa, Okla.

[73] Assignee: Amoco Production Company HEAVE-PROOF ARCTIC PILING419,139 11/1934 GreatBritain.................6l/53 [72] Inventor:

Primary Examiner-Jacob Shapiro Attorney-Paul F. Hawley 221 Filed: Nov.13,1970

211 Appl.No.: 93,764

[ ABSTRACT Piling projecting at the upper part through tundra areprotected from ground movement in an upward [52] US. Cl. 52/170, 61/50,

[511 directiondueopefiodicfreezingsandthmgsofthe :61 /53 53.6 53.68 3650 tundra by being fixed to conically shaped collars extending down fromthe surface of the earth, with the base of the cone down. The conicalportion thus becomes a part of the pile, mechanically speaking. If

[58] Field of Search.........

[56] References Cited desired, the conically shaped part may be anintegral UNITED STATES PATENTS part of the pile. As the liquid part ofthe tundra sur- 1,532,734 4/1925 Dean...........................52/l7Omunding the "W P Of the pile freezes, it expands 216,970 7/l879Parks.........................6l/53 X inward against the Conical Surfaceresulting in 1,596,657 8/1926 Heber......................52/170 x adownward force of suificiem magnitude to p the 1,433,621 10/1922Hutton......,............D28/4 UX pi fr0m ea g, -e-, ng ver icallyupward due to freezing effects in the ground,

3 Claim, 3 Drawing Figures L .i. ies. amfmfiwww wmk W PATENTED I9733,703,812

FIGI

INVENTOR. GEORGE R. NEWTON A T TORNE Y HEAVE-PROOF ARCTIC PILINGBACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This inventionparticularly finds use in what is commonly called tundra, that is, anunstable earth material in which there is a considerable amount ofwater; frequently the major portion is water. Such material is referredto as marsh in regions where there is no cyclic freezing and thawing. Itis well known that during the winter months this tundra can supportquite adequately any ordinary structure, following only the usual ruleswith respect to foundations. However, under thawing conditions thesurface ice and that down a number of feet reverts to water and theresultant material has essentially no foundation properties.

In such regions it has become quite customary to locate any permanentstructures, that is, those that must have a foundation the year around,on piles which are driven down into sufficiently solid subsurfaceformations so that an adequate foundation may result. This may be aslittle as of the order of 30 feet or may be 100 feet or more. The solidmaterial may be simply permafrost, i.e., part of the marshy unstableformation which is permanently frozen, as the name indicates, or may bethe ordinarily competent type of formations used for foundations in moretemperate regions.

The use of such piling has revealed a problem not present in regionswhere the upper part of the unstable formation does not freeze, namelythat in the course of freezing quite ordinarily there is a slow gradualupward movement of the entire pile. This is not always found, but it isfound with sufficient regularity so that it has posed a very definiteproblem to construction engineers interested in erecting buildings inarctic regions. This movement is sometimes called heaving.

2. Description of the Prior Art A few rather scattered attempts tocombat this movement have been mentioned in the literature. InFoundations of Structures in Cold Regions, by F. J. Sanger, June 1969,Cold Regions Science and Engineering Monograph Ill-C4, there is astatement that wood piles are commonly placed butt down to improveanchorage against heave forces arising in the freezing active zone. G.B. Pritchard commented in his discussion on Foundations in PennafrostAreas, Permafrost lntemational Conference, Purdue University, Nov. 1l-IS, 1963, page 516, that one can use concrete piers having a taper of2 to 3 inches in 1 foot. He does not state anything with respect to thedirection in which this batter or tapering occurs, i.e., whether thepiles are placed large end up or down.

The Schutte US. Pat. No. 3,191,390 teaches that concrete columns can bepoured in place. The lowest section of the column is made in the form ofa conical section with the base of the cone at the bottom. The cone islocated not at the surface but at the bottom. The use of such a pile hasnot been taught for arctic foundations in tundra. In fact, with thisconical positioning, it would not prevent heaving.

SUMMARY OF THE INVENTION I provide a pile arrangement particularlyadapted for use in the tundra, that is, marshy areas which periodicallyfreeze and thaw. The upper part of the pile, i.e., essentially that justbelow the surface, is either integrally or separately made up of aconical portion with the big end of the cone down. If the conicalportion is separate from the rest of the pile (preferred arrangement)then this portion (called a conical collar) is clamped to theessentially cylindrical pile itself, so that the forces that are appliedto one are applied to the other. The conical portion is preferably setin advance in a roughly cylindrical hole prepared in the tundra, if theground is frozen, or is simply forced down if the tundra is unfrozen,until at least the major part of the cone is beneath the surface of theground. Preferably it extends to the permafrost.

If a conical collar is used, it is provided with an axial hole throughit, large enough to permit the pile to be driven through it (preferredarrangement) or for the cone to be threaded over the pile after it isdriven, if necessary. Concrete piles, preferably reinforced concrete,can be prepared with the conical portion integral, in which case theentire pile is driven simultaneously. This arrangement is employedchiefly in regions in which the water portion of the tundra considerablyexceeds the solid portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show a cross sectionthrough tundra illustrating the method of placing a conical pile collarin accordance with my invention and illustrating the resultant pile withconical portion after it has been prepared ready for the foundation.FIG. 2 is shown at right angles to FIG. 1.

FIG. 3 shows a cross section of tundra with an integral pile withconical upper portion, which has been driven into the tundra inpreparing a foundation for a structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT As mentioned above, wood,concrete, and metal piles have been all used in preparation offoundations in tundra. Generally these show a tendency to heave upon thefreezing of the water portion of the tundra about the piling. This istrue even though the lower portion of the pile has been set intonormally quite competent subsurface formation, from the standpoints ofordinary soil engineering. I believe that this periodic heaving is theresult of the liquid part of the tundra freezing, and, accordingly,expanding as it freezes about the pile. This can apply a pronouncedlifting effect to the pile and tend to draw it periodically out of theearth. In addition to the squeezing action, the expansion also, Ibelieve, causes the tundra to heave vertically upward and, because ofits tight grip on the pile, carries the pile upward. Upon thawing thesurface subsides leaving the pile protruding above the surface more whenoriginally placed.

In order to overcome this effect I provide the ordinary piling with aconically shaped portion, the large end of which is oriented down, theconical portion being buried in the tundra with the top substantially atthe tundra surface. Preferably this conically shaped portion is made inwhat can be called a collar, i.e., is a completely detachable conicallyshaped member with a hole through it to accommodate the pile, andclamping means to attach it very securely to this pile.

Such a collar is shown in FIG. -I. The body 11 contains an axial hole 12which extends completely throughout this member. At the top is a clamp13 suitably provided with bolts 18 by which the clamp can be compressedabout apile such as pile 14 shown in FIG. 2. Y

The conical outer surface of the body of the conical collar is inclinedoutward at at least substantially a constant directorix angle 0. Iprefer to bury the cone deep enough so the maximum cone diameter occursat or below the zone of constantly frozen material (called permafrost).The cone diameter should be a maximum of at least three pile diametersor more. Thus the directorix angle may be as small as 3 and as large as20 to 30.

No particular form of clamp is required. That shown in FIGS. 1 and 2simply consists of a metal member 13 with an axial slot 15 forming theboundary of two lips 16 and 17 (simple extensions of the outwardsurface) which are perforated at ,at least two points for insertion ofclamping bolts 18. When these bolts are tightened the upper part ofmember 11 compresses about the pile 14 and is thus clamped to this pile.

The conical collar body 11 may be made integrally or metal, or it can bemade of wood or of reinforced concrete with the clamping portion 13forming an extension of numerous reinforcing rods 20 in the body 1 1, asin the version shown in FIG. 1. Preferably the conical portion is solidalthough in cases of necessity for extreme lightness, as where theconical collar must be air transported to a remote arctic region, onecan form the body 1 1 from a conically shaped metal skirt," acylindrical section of pipe slightly larger than the pile diameter, andtriangular shaped metal ribs radially oriented between the pipe and theskirt and welded to both, to transmit the downward force from the outerpart of the skirt to the pile itself. 1 FIGS. 1 and 2 also illustrate apreferred method 0 placing the pile, including the conically shapedportion. In this embodiment, a substantially cylindrical hole 21 hasbeen dug into the tundra 22 to a depth essentially equal to the axiallength of the conical portion of the collar. Collar lengths of 10 to 15feet frequently pemiit the bottom of the collar to be located in thezone of permafrost, which is desirable. The conical collar has then beenlowered into this hole, with the clamp 13 still protruding above thesurface for easy access to the bolts 18. The clamping bolts are, ofcourse, loose at this point.

The pile 14 is then inserted through the hole 12 and driven by anyconventional pile driving means until it is securely anchored in acompetent formation, such as formation 23. Only after the pile 14 hasbeen securely anchored in position are the clamping bolts 18 tighteneddown to clamp the conical collar 11 to the pile 14. This completes thesimple procedure.

When temperatures below freezing solidify the liquids that haveaccumulated in hole 21 about the clamping collar 11, the approximatelyradially inward forces exerted by this freezing action apply anessentially downward force through the clamp 13 to the pile l4 andoppose any tendency of this pile to heave, or

7 move gradually upward under freezing conditions.

It is not essential that one employ a detachably mounted collar 1 1. Forexample if metal piles are used,

at times it is advantageous to dispense with the clamp 13 and simplyweld the upper portion of the conical collar to the metal pile. Also,and as shown in FIG. 3, at times the entire pile and conical portion aremade integral. In this particular illustration the conical portion 24formed of reinforced concrete is integral with the cylindrical portion25, there being preferably a plurality of steel reinforcing barsdiagrammatically indicated at 26 spaced throughout both the conicalportion 24 and cylindrical portion 25. In this case the procedure maysimply be to fonn a cylindrical hole 21 and then drive the pile. If thetundra is mainly water at this point, of course there is no need to forma cylindrical cavity 21; one simply drives the entire pile which formsits own cavity 21 by the lower conical end of portion 24 forcing its waythrough the tundra.

While the conical collar of FIG. 1 wasshown with a flat bottom, I preferto have the bottom section another frustum of a cone inverted withrespect to the upper conical part. This is shown in FIG. 3 also. Theconical base should taper back at an angle (1 of around 30 to 45. Sucharrangement is desirable whether the integral cone and pile arrangementbe used as in this figure, or the conical collar shown in the first twofigures be employed. Such bottom taper also helps position such a collaror cone plus pile to the proper depth. It also facilitates driving thecone (in either arrangement) with or without a pilot hole. If the solidspart of the tundra is mobile and the water portion is thawed, one canfrequently simply force the conical collar down into position as shownin FIG. 1 without any previous excavation.

For simplicity this specification has dealt with conical members andcollars. Many of the advantages of this invention can be achieved usinga pyramidal form for the section adjacent the surface of the tundra.Usually such a section, basically amounting to three or more oppositelydisposed wedges with the tin edge of the wedge at the surface, issomewhat more difficult and expensive to construct and with no apparentmajor advantage over the shapes already discussed.

It should be understood that the essential point of this invention isthe provision of a tapered body portion surrounding and connected to thepile, the top of this portion being located adjacent the top of thetundra and being in force-transmitting relationship to the pile or thelike such that the expansive forces of forming ice about such taperedbody portion provide a downward force substantially sufiicient toovercome any tendency of the pile to heave.

I claim:

1. A tapered member for use in minimizing heave in a pile driven intoperiodically freezing and thawing tundra comprising a. a tapered solidbody the transverse dimensions of which gradually increase from top tobottom thereof, said body defining a central axial hole large enough forthe pile to pass through, the bottom part of said tapered bodydecreasing abruptly to the dimensions of said central axial hole, and

b. clamping means connected to said tapered body for fixing said body inforce-transmitting relationship to said pile.

2. Apparatus in accordance with claim 1 in which said tapered body formssubstantially the frustum of a 3. Apparatus in accordance with claimt2in which said tapered body forms substantially the frustum of a cone,the directorix angle of which is within the range of approximately 3 toapproximately 30; the maximum diameter of said tapered body being atleast three times the diameter of said pile.

1. A tapered member for use in minimizing heave in a pile driven intoperiodically freezing and thawing tundra comprising a. a tapered solidbody the transverse dimensions of which gradually increase from top tobottom thereof, said body defining a central axial hole large enough forthe pile to pass through, the bottom part of said tapered bodydecreasing abruptly to the dimensions of said central axial hole, and b.clamping means connected to said tapered body for fixing said body inforce-transmitting relationship to said pile.
 2. Apparatus in accordancewith claim 1 in which said tapered body forms substantially the frustumof a cone the directorix angle of which is within the range ofapproximately 3* to approximately 30*, and said bottom part of said bodyis reverse tapered with respect to the upper portion thereof with adirectorix angle substantially greater than that of said tapered body,so that axial length of said bottom part is substantially smaller thanthat of said tapered body.
 3. Apparatus in accordance with claim 2 inwhich said tapered body forms substantially the frustum of a cone, thedirectorix angle of which is within the range of approximately 3* toapproximately 30*; the maximum diameter of said tapered body being atleast three times the diameter of said pile.